Chemoattractant cytokines, Chemoattractant cytokines or chemokines are a family of proinflammatory mediators that are released by a wide variety of cells to promote recruitment and activation of cells such as T and B lymphocytes, eosinophils, basophils, and neutrophils (Luster et al. New Eng. J. Med, 1998, 338, 436). The chemokines are related in primary structure and contain four conserved cysteines, which form disulfide bonds. The chemokine family includes the C—X—C chemokines (α-chemokines), and the C—C chemokines (β-chemokines), in which the first two conserved cysteines are separated by an intervening residue, or are adjacent, respectively (Baggiolini, M. and Dahinden, C. A., Immunology Today, 1994, 15, 127).
Chemokines exert their biological activity by binding to specific cell-surface receptors belonging to the family of G-protein-coupled seven-transmembrane-domain proteins (Horuk, Trends Pharm. Sci. 1994, 15, 159) which are termed “chemokine receptors”. On binding their cognate ligands, chemokine receptors then transduce signals important for the development and trafficking of specific leukocyte subsets (Baggiolini, et. al., Nature 1994, 15, 365). The chemokines and their cognate receptors have been implicated as being important mediators of inflammatory, and allergic diseases, disorders, and conditions, as well as autoimmune pathologies such as rheumatoid arthritis and atherosclerosis (see, Carter, Current Opinion in Chemical Biology 2002, 6, 510; Trivedi et al., Ann. Reports Med. Chem. 2000, 35, 191; Saunders et al., Drug Disc. Today 1999, 4, 80; and Premack et al., Nature Medicine, 1996, 2, 1174).
The first receptor for the C—C chemokines that was cloned and expressed binds the chemokines MIP-1α and RANTES. Accordingly, this MIP-1α/RANTES receptor was designated C—C chemokine receptor 1 (also referred to as CCR-1 or CKR-1; Neote, K., et al., Cell, 72:415-425 (1993); Horuk, R. et al., WO 94/11504, May 26, 1994; Gao, J.-I. et al., J. Exp. Med., 177:1421-1427 (1993)). CCR1 also binds the chemokines CCL2 (MCP-1) CCL4 (MIP-1β), CCL7 (MCP-3), CCL8 (MCP-2), CCL13 (MCP-4), CCL14 (HCC-1), CCL15 (Lkn-1), CCL23 (MPIF-1). (Murphy P. M. et al., International Union of Pharmacology. XXII. Nomenclature for Chemokine Receptors, Pharmacol. Reviews, 52:145-176 (2000)).
Small molecule antagonists of the interaction between C—C chemokine receptors (e.g., CCR1) and their ligands, (e.g., CCL2 (MCP-1) CCL3 (MIP-1α), CCL4 (MIP-1β), CCL5 (RANTES), CCL7 (MCP-3), CCL8 (MCP-2), CCL13 (MCP-4), CCL14 (HCC-1), CCL15 (Lkn-1), or CCL23 (MPIF-1)), would inhibit those processes or cellular responses mediated by the binding of a chemokine to CCR1. Accordingly, these compounds would inhibit those pathogenic processes “triggered” by receptor ligand interactions (e.g., leukocyte migration, integrin activation, transient increases in the concentration of intracellular free calcium [Ca++]i, and/or granule release of proinflammatory mediators) and would be useful in the treatment of diseases, conditions, or disorders mediated by these pathogenic processes. Indeed, there has been substantial interest in the discovery and development of antagonists of CCR1 for a treatment of a variety of disorders including, but not limited to rheumatoid arthritis, multiple sclerosis, transplant rejection, and allergic inflammation (see, Cascieri et al., Curr. Opin. Chem. Biol. 2000, 4, 420; Onuffer et al., Trends Pharmacol. Sci. 2002, 23, 459; and Pease et al., Expert Opin. Investig. Drugs 2005, 14, 785). Additionally, studies have suggested that CCR1 antagonists would be useful for the treatment of cancer, including multiple myeloma, and for the treatment of other bone disorders resulting from the chemotactic and other responses of osteoclasts to the CC chemokine macrophage inflammatory protein (MIP-1α) (see, Exp. Hematol. 2005, 33, 272; J. Clin. Invest. 2001, 108, 1833; Cancer 2003, 97, 813; and Blood 2003, 102, 311 and references cited therein).
There remains a need, however, for the discovery and development of antagonists of CCR1 for use in the treatment of diseases, conditions, and disorders mediated by the interaction of chemokine receptors and their ligands.